Field of the Invention
The present invention relates generally to aviation mechanics' tools for helicopter repair, and more particularly to a tool for replacing spherical bearings, and still more particularly to a swashplate spherical bearing tool kit.
Background Discussion
The Bell 206 JetRanger, along with its military expression in the Bell OH-58 Kiowa Warrior, includes spherical bearings connecting the collective lever and/or the fixed swash to the pitch-and-roll servos through push/pull tubes. The proper functioning of these bearings is critical to airworthiness and flight safety. Any damage or significant wear will adversely affect control and operation in flight, and in-flight failure is catastrophic. Therefore, the bearings are inspected and serviced regularly and serviced both prophylactically and in response to any discernible damage or significant wear, invariably through a wholesale replacement of the part. Unfortunately, the replacement procedure is both labor- and time-intensive and entirely undermines the mission readiness of the involved aircraft. As any soldier or civilian first responder knows, aircraft downtime ultimately translates into lost lives.
For the Bell206/OH-58, the procedure presently used to replace worn or damaged spherical bearing requires removal of the swashplate assembly so that the bearing can be swapped out in the repair shop, rather than in the field. In turn, the swashplate removal requires removal of the main rotor head and rotor blade assembly. This requires at least two mechanics and involves an expenditure of about two man-hours for each mechanic. Next, the forward transmission cowling must be removed. This requires approximately 20 minutes for a skilled mechanic. Then the main rotor control push/pull rods must be disconnected from the swashplate. Each rod disconnection requires about five minutes. The swashplate drive link is also disconnected from the transmission, and this requires about 30 minutes. At this point the filleting and fairing sealing compound (typically ProSeal) must be cut from the swashplate support pylon, and the support pylon is then disconnected from the transmission. Thereafter, the collar set is removed from the main rotor mast assembly, and only then can the swashplate assembly be removed for bearing replacement.
Thus, it takes trained mechanics at least four to five hours simply to get the swashplate prepared for the bearing replacement task, which must then be done on the bench in a fixture (a bench clamp, for instance) in the repair shop, as the bearing must be pressed out and then replaced.
Once the spherical bearing is replaced in the swashplate, the entire swashplate assembly must then be reinstalled, after which it must be inspected by a Technical Inspector and the aircraft then flown by a qualified test pilot. With the mechanical tasks involved and the critical path scheduling of inspectors and pilots considered, the simple spherical bearing replacement job is a three-to-four day job requiring approximately 72 total man-hours.
The inventive tool eliminates all of the above-described preliminary work. The inventive tool kit is sufficiently compact to permit mechanics to access and replace swashplate push/pull tube bearings or any other spherical bearings in the swashplate control system within the very confined area of the air induction fairing and swashplate cowling, without removing the fairing and cowling. Simply put, the inventive tool accomplishes the bearing replacement task while the swashplate is still installed in the aircraft. Further, it can be used to replace the tail rotor control spherical bearings. This will save countless man hours of work and will get the aircraft mission ready in a fraction of the time required when using the conventional procedure and tool set.